Is Excel Online still as slow as it used to be a couple of years ago? I remember reading (perhaps here on HN) about how it basically spun up a headless Excel instance for each user since they couldn't extract and decouple all the functionality necessary to run some of the more advanced features.
> Excel is a different world and a big-big elephant that won't likely be rewritten any years soon. Think of a code that is maintained over 30 years. Literally, developers are still maintaining code written in the 90s. Trying to bring Excel to the online world made MS create an architecture of html frontend which communicates with a dll session behind the scenes. As weird as it sounds, this dll lives as long as the browser has the spreadsheet opened. Think of it as MS raising VM for every excel file that is opened over the internet. While this is not very cost effective (saying the least) and not very performance friendly (hey ma! I made an understatement) this allowed them to move forward with Excel online very quickly by having a UI communicating with the bloatware dll that runs on the background in Azure. Summarizing Excel, it probably won't also be rewritten in js.
EDIT: https://news.ycombinator.com/item?id=17304660 (June 2018)
> Excel is a different world and a big-big elephant that won't likely be rewritten any years soon. Think of a code that is maintained over 30 years. Literally, developers are still maintaining code written in the 90s. Trying to bring Excel to the online world made MS create an architecture of html frontend which communicates with a dll session behind the scenes. As weird as it sounds, this dll lives as long as the browser has the spreadsheet opened. Think of it as MS raising VM for every excel file that is opened over the internet. While this is not very cost effective (saying the least) and not very performance friendly (hey ma! I made an understatement) this allowed them to move forward with Excel online very quickly by having a UI communicating with the bloatware dll that runs on the background in Azure. Summarizing Excel, it probably won't also be rewritten in js.